Clinical records

Over the past 3 years, we have identified five cases of coronary syndromes attributable to a left subclavian stenosis proximal to a left internal mammary artery (LIMA) graft for coronary artery disease. All occurred in men aged between 56 and 73 years, presenting a median of 52 months (range, 26–138 months) after coronary artery bypass grafting. One patient presented with stable angina, three had unstable angina, and one had a non-ST elevation myocardial infarction. Arm claudication was present in one patient. Three of the five patients had an exercise or pharmacological stress test — all with anterior wall ischaemia.

At cardiac catheterisation, the diagnosis was recognised by careful comparison of the pressure tracings in the subclavian artery and aorta. All patients had a significant pressure gradient across the subclavian stenosis (median, 35 mmHg; range, 20–85 mmHg), measured by a 5F or 6F diagnostic catheter, and a significant angiographic stenosis (median, 70%; range, 50%–80%). Non-invasive left arm blood pressure measured at the time of cardiac catheterisation was substantially lower than aortic pressure (> 20 mmHg difference in all patients). Retrograde flow up the LIMA graft during native left coronary angiography, a characteristic of subclavian steal, occurred in one of the five patients (Figure 1).

All patients were treated with percutaneous stenting, using 9–10 mm balloon expandable stents, with successful abolition of the pressure gradient in the proximal subclavian artery (Figure 2). The difference in non-invasive blood pressures between the arms after stenting was less than 5 mmHg in all patients. All patients had relief of their angina symptoms over a median follow-up of 20 months (range, 5–29 months).

1 A: Subtracted angiogram showing the subclavian stenosis prior to the left internal mammary artery (LIMA) origin. B: Selective left coronary angiogram showing flow down the left anterior descending artery (LAD) (1) then retrograde up the LIMA (2 and 3). C: Diagram showing the relationship of the stenosis to the left vertebral and LIMA origins.

2: Angiograms of the left subclavian stenosis before (A) and after (B) stenting, showing the improvement in antegrade LIMA flow. The intra-arterial subclavian pressure tracings are shown below the angiograms. Before stenting (left) the pressure tracing is blunted, while after stenting (right), there is an improvement in blood pressure and normalisation of the arterial waveform.